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FG Turbo Randomly Stuck Rich


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Hey all,

A weird issue that is doing my head in. 

Giving the car a half throttle squirt getting into some boost but not full throttle, then backing off, the air fuel ratio returns to 14.7 after tipout however quickly drifts off to 10.5 and stays there at all loads-idle, accelerating, cruising. This rich afr lasts for around a minute then returns to stoich. 

Now on the logging during this period I can see injector ms has definitely increased but nothing seems to trigger/change during this rich condition. 

The fuel pressure remains constant and is not sticking high. Fuel source remains closed loop the whole time. Torque sources remain driver demand.

Short term/Long term trims are close enough to 1.0 all the time but during this period the short term winds out to 0.70-with no reason why, then a minute later its back to 1.0 and car is no longer rich. Seems to be the only thing in the log changing during this period.

All vitals/temperatures read as normal. 

The car misfires during this period as its so rich. 

Flat out back to back dyno runs or drag strip runs this issue never shows it self. Literally only with squirts of less than full throttle. 

Any ideas?


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That is normal. It is an extension of exhaust/catalytic/turbo converter protection. There is a timer you can adjust to remove it. Most likely your injector scaling is off, it should be mid 0.7s or 0.8 from memory, but it is extremely rich.

Mick Egan posted about it on here a while ago and we did an explanation, I'm not sure what the thread was called unfortunately.

It is there for a good reason on stock cars however. A single WOT run up mt hotham with a trailer would destroy a brand new catalytic converter without it was what I was told (in a stock car).

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I orginally thought it was some sort of temperature issue, so disabled all protections cat, exhaust and turbo, and it still does it. Logging the temperatures they are all well below where factory temp protection would come in and even further from where i have moved it too. And to back this up pull after pull on the dyno it never comes up even when the temps increase. 

This issue only appears after half throttle, couple second pulls.

If it was going into this temperature protection mode would it not show up in the data logger?

Edited by alfa5252
Wrong word
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There is a specific scalar that basically says how long to hold rich after a specific load is hit. From memory it had a timer value and a threshold. It was seperate to exhaust/cat protection and was 20 seconds from memory. There was also another scalar that said what lambda to hold it at.

Export all the scalars to excel using Utility -> View All Scalars -> Ctrl + A -> Ctrl + C then open excel and Ctrl + V, you can then filter on scalars that are around the 20 second mark and have units of S.

Also do some searching on here, Mick Egan definitely posted about it (maybe it was on another forum or FB but he would know).

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Apprectiate your help Roland,

Closest i can find is

auf11247 Max time an A/F excursion can be active to test d.s. EGOS                  20 Secs

with related scalar auf12263 LAMBSE to command while forcing an A/F excursion to force the d.s. EGO sensors r                        which is 0.85.


auf11249 Time to ramp bank1 rich and bank2 lean during the KOER EGO test.               20 Secs


I've also spent time searching key words on this forum and a couple other ford related forums with no luck.

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Ok, none of above changed anything. 

Spoke to Mick Egan his problem was different and did not last any where near as long. 

Commanded final lambda floats between 0.70 and 0.80. for around a minute before this issue resolves it self and LTFT stays 1.0 and in closed loop fuel source. 

Could there be something hidden to do with massive pressure difference between Intake Air Pressure sensor and Map sensor? 

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In the interests of time have got you tried putting the tune back to stock as close as possible with just injector data, wastegate duty set to 0 etc, the bare minimum to run safe and correct lambda? 

If I get time I'll have a look at the tune. It's very odd indeed and something I've never heard of before. 

Edit: you say no flex. Could you datalog stoich and see if that is changing? 

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56 minutes ago, alfa5252 said:

Yes so file posted is pretty stock


That file is far from stock. There are heaps of O2 related parameters changed that would never normally be touched when tuning a vehicle. I would revert all of that before looking further, as there are too many things changed.

That aside, you have 175 for the high slope which says you have 2200cc injectors @ 4 bar. Your low slope is 408, it should be closer to 180.

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Yes you're right, they're just changes i have made chasing this issue. Does it with them on or off. 

Injector data probably looks wrong for 1700cc at 4 bar but its correct and the car runs great. Trims are within 2-3%.

They are xspurt injectors and data supplied for slopes has not been changed. 

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32 minutes ago, alfa5252 said:

They are xspurt injectors


Xspurt only show a 1000cc injector and a 1550cc injector @ 3 bar. Neither of those adds up to 1700cc @ 4 bar. Is there a link to the injectors you bought?

Another thing that isn't normally changed is the injector multipliers, auF16649, auF0122, auF0120. These have all been changed to 1, try leaving these stock. You may have to adjust the low slope to compensate. If you're getting data related to this from an online editable spreadsheet, you'll find that these are often incorrect.

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Ignore the deadtime numbers being different as of course the spreadsheet is never right but this is the exact set, they flow 1710cc at 4 bar. 

Many ways to skin a cat end of the day LTFT is good and car drives well. Apart from this issue of course :)


Xspurt Injectors.jpg

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That's what we're here to find, the issue. Dead cats aside, the injector data in the tune you posted doesn't look right to me. If you don't want to try my previous suggestion that's fine, it's neither here nor there to me. It's what I would do tho and if it doesn't work then I would look elsewhere.

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I've had similar symptoms when an O2 sensor was on the way out. It would go extremely rich, seemingly at random.

Initially the wiring had melted which was causing an intermittent short circuit. After that was fixed I'm sure it happened again and a sensor swap got it sorted. It was a long time ago but that's the gist of it.

You should log the O2 sensor voltage to see the correlation between it and the rich condition.

It's pretty easy to swap to a known good sensor, might be worth a shot.

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